The intestinal absorption of separately labeled simple and conjugated folate is measured by the technique of jejunal perfusion in patients with tropical sprue, celiac sprue, and alcoholism and supplemented by assays of jejunal folate conjugase. The effect of dietary folate deficiency and alcohol ingestion upon intestinal folate absorption and enzyme activities is measured in non-human primates (Macaque Radiata) studied after diets in which folate and ethanol content are varied. Subcellular fractionation techniques are employed to determine the jejunal mucosal site of activity of folate conjugase. In vitro studies using isolated mucosal epithelial cells and everted gut sacs are employed to measure the sequence of digestion and mucosal transport of conjugated folate. BIBLIOGRAPHIC REFERENCES: Halsted, C.H., Reisenauer, A.M., Back, C., Gotterer, G.: In vitro uptake and metabolism of pteroylpolyqlutamate by rat small intestine. J. Nutrition, 1976. Halsted, C.H., Reisenauer, A.M., Gotterer, G.: Process of digestion and absorption of pteroylpolyglutumate. In Proceedings of A Workshop on Human Folate Requirements. H. Broquist, editor. National Academy of Science, 1976.